Crystal Growth and Structure Determination of Oxygen-Deficient Sr6Co5O15
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- 作者：Junliang Sun ; Guobao Li ; Zhaofei Li ; Liping You ; Jianhua Lin
- 刊名：Inorganic Chemistry
- 出版年：2006
- 出版时间：October 2, 2006
- 年：2006
- 卷：45
- 期：20
- 页码：8394 - 8402
- 全文大小：275K
- 年卷期：v.45,no.20(October 2, 2006)
- ISSN：1520-510X
文摘
Large single crystals of oxygen-deficient Sr6Co5O15-
compounds, i.e., Sr6Co5O14.70 and Sr6Co4.9Ni0.1O14.36, wereobtained by using K2CO3 flux in the presence of additives of transition metal oxides. The single-crystal structuredetermination shows that the structures of Sr6Co5O14.70 and Sr6Co4.9Ni0.1O14.36 crystallize in the space group R
and can be described as one-dimensional face-sharing CoO3 polyhedral chains and Sr cation chains. Unlike theother known 2H-perovskite-related oxides in which the polyhedral chains consist of octahedra (Oh) and trigonalprism (TP), the structure of Sr6Co5O14.70 and Sr6Co4.9Ni0.1O14.36 contain Oh and intermediate polyhedra (IP) and canbe attributed to a general structure formula A6A'2B3O15-, which is closely related to the known A6A'B4O15 phasesby shifting of a B atom and the O3 triangle along the c axis. Further study on O3 reveals that this oxygen positionsplits into two independent positions, corresponding to polyhedral geometry of IP and TP, respectively. Therefore,the polyhedral chain in the structure should be more precisely described as a random composite of the 4Oh + TPand 3Oh + 2IP. This model is used to interpret the magnetic properties, although not quantitatively. The 4-Dstructure analysis was also conducted for both Sr6Co5O14.70 and Sr6Co4.9Ni0.1O14.36 with a commensurate modulatedstructure in a 4-D superspace group, Rm(00
)0s, = p/k = 3/5. By considering the same 4-D superspacegroup Rm(00)0s but different t-phases, one can understand the structure relationship between Sr6Co5O14.70 andSr6Rh5O15.
compounds, i.e., Sr6Co5O14.70 and Sr6Co4.9Ni0.1O14.36, wereobtained by using K2CO3 flux in the presence of additives of transition metal oxides. The single-crystal structuredetermination shows that the structures of Sr6Co5O14.70 and Sr6Co4.9Ni0.1O14.36 crystallize in the space group Rand can be described as one-dimensional face-sharing CoO3 polyhedral chains and Sr cation chains. Unlike theother known 2H-perovskite-related oxides in which the polyhedral chains consist of octahedra (Oh) and trigonalprism (TP), the structure of Sr6Co5O14.70 and Sr6Co4.9Ni0.1O14.36 contain Oh and intermediate polyhedra (IP) and canbe attributed to a general structure formula A6A'2B3O15-, which is closely related to the known A6A'B4O15 phasesby shifting of a B atom and the O3 triangle along the c axis. Further study on O3 reveals that this oxygen positionsplits into two independent positions, corresponding to polyhedral geometry of IP and TP, respectively. Therefore,the polyhedral chain in the structure should be more precisely described as a random composite of the 4Oh + TPand 3Oh + 2IP. This model is used to interpret the magnetic properties, although not quantitatively. The 4-Dstructure analysis was also conducted for both Sr6Co5O14.70 and Sr6Co4.9Ni0.1O14.36 with a commensurate modulatedstructure in a 4-D superspace group, Rm(00)0s, = p/k = 3/5. By considering the same 4-D superspacegroup Rm(00)0s but different t-phases, one can understand the structure relationship between Sr6Co5O14.70 andSr6Rh5O15.